Water-soluble, isolable gold clusters protected by tiopronin and coenzyme A monolayers
Water-soluble, isolable gold clusters protected by tiopronin and coenzyme A monolayers
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DOI：
10.1021/la9808420
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发表时间：
1999-01-05
期刊：
影响因子：
3.9
通讯作者：
Murray, RW
中科院分区：
文献类型：
--
作者：
Templeton, AC;Chen, SW;Murray, RW
可分离的，水溶性的金簇的硫普罗宁（硫普罗宁-MPCs）或辅酶A（CoA-MPCs）的单层保护的合成的程序相当简单的烷硫醇单分子层保护的金簇的Brust合成。高分辨率透射电子显微镜显示，像他们的烷硫醇盐-MPC对应物，硫普罗宁-MPC的平均核直径可以通过改变反应中采用的硫普罗宁：Au摩尔比来系统地控制。硫普罗宁-MPC的紫外-可见光谱表现出pH和核心大小的表面等离子体带的位置和强度的依赖性，分别。硫普罗宁-MPC的热重分析给出了每个簇的硫普罗宁配体的平均数目;例如，平均核尺寸为1.8 nm的硫普罗宁-MPC（类似于Au-201）被平均85个硫普罗宁配体保护。H-1 NMR揭示了解释为反映连接位点（平台，缺陷）和/或配体流动性限制的差异的光谱特征的大小依赖性的演变。红外光谱揭示了单层中的强氢键，并提供了簇间缔合的证据，酸/碱滴定产生的pK（A）值与存在电荷屏蔽支持电解质时的游离配体相似，但在不存在电荷屏蔽支持电解质时更高。相同的分析方法也适用于CoA-MPC。
Isolable, water-soluble gold clusters protected by monolayers of tiopronin (tiopronin-MPCs) or coenzyme A (CoA-MPCs) were synthesized by a procedure of comparable simplicity to the Brust synthesis for alkanethiolate monolayer-protected gold clusters. High-resolution transmission electron microscopy shows that, like their alkanethiolate-MPC counterparts, the average core diameters of tiopronin-MPCs can be systematically controlled by varying the tiopronin:Au mole ratio employed in the reaction. The UV-vis spectra of tiopronin-MPCs exhibit pH and core size dependency of the surface plasmon band position and intensity, respectively. Thermogravimetric analysis of the tiopronin-MPCs gave average numbers of tiopronin ligands per cluster; for example, tiopronin-MPCs with an average core size of 1.8 nm (similar to Au-201) are protected with an average of 85 tiopronin ligands. H-1 NMR reveals a size-dependent evolution of spectral features interpreted as reflecting differences in attachment sites (terrace, defects) and/or restriction in ligand mobility. Infrared spectroscopy reveals strong hydrogen bonding in the monolayer and provides evidence for intercluster association, and acid/base titrations produce pK(A) values similar to the free ligand in the presence of a charge-screening supporting electrolyte, but higher in its absence. The same analytical methods were also applied to CoA-MPCs.